Enantioselective synthesis of benzocyclic α,α-dialkyl-amino acids: new insight into the solvent dependent stereoselectivity of the TMSCN addition to phenylglycinol derived imines

Gallium (III) triflate catalyzed efficient Strecker reaction of ketones and their fluorinated analogs

“…Efficient, clean, and direct three-component Strecker reaction using ketones is difficult. Quite often, these reactions have to be carried out stepwise (preparation of imines first followed by cyanide addition) (2,3) or under high pressure conditions (6,7). Use of ammonia or ammonium salts in the presence of cyanides has been described (8)(9)(10)(11)(12)(13).…”

“…However, successful three component Strecker reactions using ketones and fluorinated ketones are rare (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Fluorinated amino acids are becoming increasingly important in pharmaceuticals and other biological applications (15)(16)(17)(18)(19)(20)(21), such as the development of anticancer drugs for the control of tumor growth and drugs for the control of blood pressure and allergies (22).…”

Recent progress on the stereoselective synthesis of cyclic quaternary α-amino acids

“…Basic hidrolysis of diastereoisomerically pure 104 , obtained after chromatographic separation, afforded the quaternary α-amino acid ( S , S )- 106 in 91% yield (Scheme 25). 104…”

Candida antarctica Lipase B in a Chemoenzymatic Route to Cyclic α‐Quaternary α‐Amino Acid Enantiomers

“…[15] This knowledge was used to determine which enantiomer of the present substrates reacts faster in the kinetic resolution with CAL-B. For this purpose, enantiopure 8a, which was obtained from enantiopure 7a, was transformed into the corresponding compound 9 by known methods, as described in the Exp.…”

“…Section (Scheme 2). [15] The S absolute configuration of the obtained acid was assigned based on its optical rotation {[α] D 24 = +107.1 (c = 0.96, MeOH)}. The S absolute configuration is also in accordance, for instance, with the R enantiopreference previously observed in the CAL-B-catalyzed hydrolysis of 1,2,3,4-tetrahydroisoquinoline-1-carboxylic esters as determined by the Cahn-Ingold-Prelog priority rules.…”